Richard Keogh marked his 200th Derby County appearance by scoring the winning goal as the Rams defeated Grimsby Town to secure their passage through to the second round of the EFL Cup.

The defender, who also turns 30-years-old later this week, guided a deep cross into the back of the net at the far post as Nigel Pearson’s side made their second half dominance count.

Grimsby threatened to take the contest into extra time as they piled on the pressure in added time with a series of corners, but Derby survived the onslaught to secure their first competitive victory of the new season.

Fresh off of the back of their opening day victory over Morecambe, their first in league football since regaining their league status, Grimsby, unsurprisingly, started with an air of confidence at the iPro Stadium.

Moving the ball across the park, Paul Hurst’s side were fearless in possession, content to try and pick their way through the Derby lines in a bid to create their chances.

Though Scott Carson’s goal was never troubled, neither was James McKeown’s in the opening stages. It represented a spirited start for the League 2 outfit on what Hurst, the Mariners’ boss, had described as a ‘big occasion’ for his players.

Inside the first 15 minutes, Darren Bent had two half chances, firstly scuffing a left foot shot wide, before he very nearly latched on to a wayward pass back to McKeown – resulting in the goalkeeper having to rush out to clear the danger.

On 27 minutes, Johnny Russell, restored to the starting line-up, lashed a low effort well wide after intercepting a pass deep inside Grimsby territory as the Rams began to dictate proceedings, but against a stubborn midfield and defence, space was very limited.

As Pearson’s men began to up the tempo, more chances fell their way.

Craig Forsyth, returning to the fold following the birth of his first child, looped a header into the arms of McKeown from a set piece, whilst Will Hughes’ poked effort was also saved by the goalkeeper.

The impressive Nick Blackman, twice, saw efforts go wide, whilst McKeown had to be alert to push a left shot away as the hosts finished the stronger at the iPro Stadium.

Into the second half and the Rams picked up where they left off, penning Grimsby deeper and deeper into their own half as they sought an early goal.

Bent guided a Cyrus Christie cross from the right wide and Russell saw a bending effort tipped over by the far busier McKeown.

Increasingly looking more of a threat, Blackman drove another drive wide of the ‘keeper’s far post and Bent, this time from inside the six-yard box, turned another cross over the crossbar as the contest approached the hour mark.

The breakthrough finally came on 60 minutes as two of the Rams’ milestone men combined.

Bryson, making his 450th career appearance, bent a cross to the back post where the lurking Keogh, making his 200th Derby appearance, had the simple task of guiding the ball into the back of the net.

From there, Derby were the only side looking likely to add to the scoreline as the Rams' confidence was raised another notch across the group.

The goal continued to evade Bent as the 32-year-old headed wide, whilst substitutes Tom Ince and Jacob Butterfield shot over the crossbar from inside the area too.

At 1-0, the game was never sealed and Grimsby, through the dangerous set pieces of Ben Davies, threatened an equaliser.

Deep into added on time, Carson saved twice, once from McKeown, the goalkeeper, whilst the ball was also hooked off the line as the Rams survived the late onslaught to secure their safe passage through to the second round of the EFL Cup.

Derby County: Carson, Christie, Keogh (C), Pearce, Forsyth; Blackman (Ince, 71), Bryson, Hughes (Hendrick, 82), Russell; Martin (Butterfield, 71), Bent

Substitutes not used: Grant, Shackell, Johnson, Lowe

Grimsby Town: McKeown, Davies (C), Andrew, McAllister (Browne, 54), Pearson, Chambers (Bolarinwa, 80), Bogle, Vose (Jackson, 73), Berrett, Summerfield, Boyce

Substitutes not used: Venney, Vernon, Jones, Warrington

Attendance: 11,692 (1,734 Grimsby supporters)